Add all of the pureed fish to a large mixing bowl and add the salt as well as the cornstarch. Beat the mixture and add any remaining cream left over from the pureeing hard, until the mixture is very light and fluffy. Pour it into your buttered cake pan and set the pan down sharply to remove any air pockets.
Smooth the top of the Fiskepudding with a spatula. Preheat your oven to 350 F and use a buttered sheet of tin foil to seal the top of the mold. Place the mold in a larger, flatter baking pan and pour enough boiling water to come 3/4 of the way up the sides of the bottom pan.
The Fiskepudding should now bake on the middle rack for 60-75 minutes at 350 F. Check that the bottom mold's water simmers but not strongly boils.
